// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_COMMUNICATION_LINUX_H_
#define CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_COMMUNICATION_LINUX_H_

#include <memory>
#include <set>
#include <string>
#include <vector>

#include <sys/types.h>

#include "base/files/scoped_file.h"
#include "base/process/kill.h"
#include "base/process/process_handle.h"
#include "base/synchronization/lock.h"
#include "content/common/content_export.h"
#include "content/public/browser/file_descriptor_info.h"

namespace base {
class Pickle;
} // namespace base

namespace content {

class CONTENT_EXPORT ZygoteCommunication {
public:
    ZygoteCommunication();
    ~ZygoteCommunication();

    void Init();

    // Tries to start a process of type indicated by process_type.
    // Returns its pid on success, otherwise base::kNullProcessHandle;
    pid_t ForkRequest(const std::vector<std::string>& command_line,
        std::unique_ptr<FileDescriptorInfo> mapping,
        const std::string& process_type);

    void EnsureProcessTerminated(pid_t process);

    // Should be called every time a Zygote child died.
    void ZygoteChildDied(pid_t process);

    // Get the termination status (and, optionally, the exit code) of
    // the process. |exit_code| is set to the exit code of the child
    // process. (|exit_code| may be NULL.)
    // Unfortunately the Zygote can not accurately figure out if a process
    // is already dead without waiting synchronously for it.
    // |known_dead| should be set to true when we already know that the process
    // is dead. When |known_dead| is false, processes could be seen as
    // still running, even when they're not. When |known_dead| is true, the
    // process will be SIGKILL-ed first (which should have no effect if it was
    // really dead). This is to prevent a waiting waitpid() from blocking in
    // a single-threaded Zygote. See crbug.com/157458.
    base::TerminationStatus GetTerminationStatus(base::ProcessHandle handle,
        bool known_dead,
        int* exit_code);

    // Returns the sandbox status of this zygote.
    int GetSandboxStatus();

private:
    // Should be called every time a Zygote child is born.
    void ZygoteChildBorn(pid_t process);

    // Read the reply from the zygote.
    ssize_t ReadReply(void* buf, size_t buf_len);

    // Sends |data| to the zygote via |control_fd_|.  If |fds| is non-NULL, the
    // included file descriptors will also be passed.  The caller is responsible
    // for acquiring |control_lock_|.
    bool SendMessage(const base::Pickle& data, const std::vector<int>* fds);

    // Get the sandbox status from the zygote.
    ssize_t ReadSandboxStatus();

    base::ScopedFD control_fd_; // the socket to the zygote.
    // A lock protecting all communication with the zygote. This lock must be
    // acquired before sending a command and released after the result has been
    // received.
    base::Lock control_lock_;
    // The pid of the zygote.
    pid_t pid_;
    // The list of running zygote children.
    std::set<pid_t> list_of_running_zygote_children_;
    // The lock to guard the list of running zygote children.
    base::Lock child_tracking_lock_;
    int sandbox_status_;
    bool have_read_sandbox_status_word_;
    // Set to true when the zygote is initialized successfully.
    bool init_;
};

} // namespace content

#endif // CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_COMMUNICATION_LINUX_H_
